Okay, well first off, that's a long time regardless of whether or not you're agood host, there are no other kids, anxiety issues, or whatever. For the future, I would talk to your husband and maybe have him tell them that they can only stay for a few days, a week max. That's a big deal. Since they don't have kids, they probably really don't get it, which is a major drag for you. In the present, wow, well, maybe recruit your husband to talk to his sister. I might try and tell her something like...'hey, just so you know here's a rough guidelines of what my kids are and aren't allowed to do...a, b, c, d, etc....that way you can help me keep an eye on them..." or something. YOu don't want to make it uncomfortable, but you also don't want to make it worse for you if they're going to be there for another week! Ultimately, you're right though, you need to enforce rules they way you want, this is your house.